Production of creosoting compositions



March 15, 1932. s. P. MILLER 1,849,199

' PRODUCTION OF' CREOSOTINGCOMPOSITIONS Filed June 5o. 1927 2sheets-sheet 1 www Lk /zM-,wfw

ATroRNEYs March 15, 1932. s,l P, MULLER 1,849,199

PRODUCTION OF CREOSOTING COMPOSITIONS Filed June so, 1927 v 2sheets-sheet 2 fig' -fi 33 32 y, ,zzgl 34 gym-, iL/9 ATTORNEYS PatentedMar. 15, 1932 UNITED STATES,

IPATENT OFFICE STUART PARMELEE MILLER, OF NEW YORK,V N. Y., ASSIGNOR TOTHE BARRETT COMPANY, F NEW YORK, N. Y., A CORPORATION OF NEW JERSEYPRODUCTION 0F CREOSOTING COMPOSITION S Application led June 30,

This invention relates to improvementsin the operation otcoal-distillation plants, and more particularly coke-oven batteries, andis directed especially to the production of salable by-products by suchoperation.

In the ordinary operation of byrod ot coke ovens the gases produced by te c king operation pass from the individual ovens through uptake pipesand goose-necks to collector mains, each common to a number of the ovensof the battery, e. g., 20. The cokeoven gases which leave the-ovens attemperatures of from 600 to 700 C. or higher are cooled in the collectormain and in condensers connected therewith t-o separate tar constituentstherefrom. The se arated coal tar is commonly shipped totar-dlstillation plants Where it is subjected to distillation to producecoal tar distillates and pitches.

One of the important products produced from coal-tar is the so-calledcoal-tar solution consisting of a mixture of coal tar distillate withraw tar in the proportions of about eighty percent ot distillate toabout twenty percent of tar. This product Vis used Widely for creosotingpurposes. The prearation of this product involves, as indicated, thedistillation of large amounts of tar with the incident expense oftransporting the tar to the tar-disillation lant and the cost ofdistillation thereof. oreover, the distillation of coal tar in ordinaryexternally heated stills causes a considerable decomposition of the oilconstituents of the tar, with increase ot pitch vand free carbon, anddecrease in yield of distillate.

Itis the object of the present invention to provide a method whereby animproved product can be produced directly at the coke oven as asubstitute for ordinary coal tar solution, thus reducing the cost of theprod-v uct and saving, moreover, the loss which always results from thedistillation of tar by cracking of some of the tar constituents, andobtaining an increased yield of an improved product at decreasedexpense.

In carrying out the invention, the cokeoven plant may for the most partvbe operated in the usual manner, that isto say, the hot coke-oven gasesmay be cooled in a regu- 1927. Serial No. 202,735.V

lated manner in the collector main by sprays of ammonia liquor orammonia liquor and tar to separate from the gases some of the tarryconstituents which may be Withdrawn from the collector main and utilizedin any desired manner, for example, by distillation to separate oilconstituents therefrom and to produce pitch.

The resulting partially cooled gases can then be conducted through thelusual crossover main to the condensing system in which the gases arefurther cooled to separate tarry oils therefrom. These oils wouldnormally contain too high a proportion of tarry constituents to beuseful as substitutes for ordinary coal tar solution.

To reduce this proportion of tarry constituents the gases flowing fromthe collector main are subjected intermittently to cleaning to removetarry constituents therefrom. Thus, a portion of the gases passing tothe condensers will be clean gases, that is, substantially free fromtarry constituents, while the balance of the gases will carrysuchconstituents to the condensers. By cleaning part of the gases, e. g.,one-half to one-third of the gases, the heavier tarry constituentstherein are removed and the mingled condensate from the clean anduncleaned gases is a composite product suitable for use as a socreosoting composition. The relative proportions of clean and uncleanedgases can be regulated readily by suitable means permitting theintermittent operation of the cleaning apparatus.

The condensers employed may be of the usual wet type in which the gasesflow upwardly and countercurrent to a stream of ammonia liquor which isdivided in the condenser bythe provision of suitable battling devicestherein to ensure maximum contact between the gases and the coolingmedium. The condensed oil can -be withdrawn from the condensers togetherwith the ammonia liquor and separated therefrom in a decanter y providedfor that purpose. The gases escaping from the condensers can bedelivered to the usual exhauster and passed thence through equipment forthe recovery of ammonia, light oils, etc. 10

voil constituents in the vapor phase while the heavier tarry or pitchconstituents are con-v verted into the liquid phase in which conditionthey are separated readily by electrical precipitation.

The temperature ofthe gases should, to accomplish the intended purpose,be maintained above the dew point of the gases for the most readilycondensable oil constituent desired so that the greater portion of theoils will be retained and will be carried over with the gases from thecollector main. The electrical precipitator should be operated at lsubstantially the same temperature as the gases undergoingprecipitation.

collector main and should be insulated if necessary to avoid the loss ofheat from the The temperature of the gases leaving the collector mainand passing through the precipitator may be, for example, around 200 C.,or in some cases even higher,although in other cases it may be around160 C. or 150 C. etc. constructed so as to be capable of withstandingthe temperatures to which it is subjected in the operation as described.

The operation of an electrical precipitator consists of passing the gasto be treated between electrodes Whose difference in electricalpotential is very great. Experience has show n. that it is best to use arectified alternating current. The alternating current (the primary) issent through a step-up transformer to produce a' high potential current(the secondary) which is then rectified to an intermittentuni-directional current, for example, by means of a rotary con' verter.The `rectified current is delivered from the converter to the electricalprecipitator at practically the potential at which it leaves thetransformer.

The electrical precipitator consists commonly of a group of verticalpipes witlra wire or rod in the centre of cach, the pipes beingvconnected to proper headers for the introduction and discharge of thegases. The pipes generally constitute the positive electrodes and theWires or rods the negative electrodes. The size of the pipes may vary,but in general y pipes of less than six inches in diameter are not used.Electrical precipitators with pipes six inches in diameter usingsecondary volt- Aupon several variables.

The electrical precipitator should be.

cipitator.

ages from 35,000 to 50,000 volts are satisfactory for the purpose ofthis invention. It is generally best to operate with maximum potentialdiierence (secondary current) between the electrodes, this maximum beingjust below the break-down voltages at which arcing occurs.

The eiiiciency of the cleaning is dependent Satisfactory clean-l ing ofthe gas maybe accomplishedl if thel time of treatment is of the order ofone second although this time may be varied widely depending upon thecharacter of the oil to be recovered from the gases passing through theprecipitator. In working with tubes nine feet long and'six inches indiameter, for example, a gas substantially free from all tarryconstituents has been' obtained with a time of treatment of from one andone-half t0 two seconds, that is to say, with a gas velocity of 6 to 4.5feet per second. This has given an efficiency of cleaning ofapproximately ninety-nine per cent. If it is desired to collect oilscontaining small amounts of tar, shorter treatment may be used, forexample, a treatment of from 0.5 to one second, that is to say, avelocity of from 18 to 9 feet per second. Since the gases after cleaningare condensed with uncleaned gases, it is not essential that thecleaning .of the gases in the electrical precipitator be thorough orcomplete. The operation can be adjusted readily to produce the desiredamount of cleaning and thus to provide upon condensation an oilproductof the desired character. The tarry or pitch constituents which areseparated in the electrical precipitator can be Withdrawn and utilizedfor any desired purpose.

It will be understood that in carrying out the invention all of thegases may be conduct-- ed through the electrical precipitator, thelatter being connected t0 the collector main and cross-over main andthat the electrical precipitator will be operated intermittently and forsufficient periods to remove that portion of the tarry constituents fromthe gases which is not required to produce a product of the desiredkind. The intermittent operation of the electrical precipitator can becontrolled manually or automatically by the provision of suitableswitches in the electrical circuit controlling the delivery ofcurrent-to the pre- Such switches may, if desired, be actuated by anysuitable mechanism so that current is supplied at intervals which may belonger or shorter as desired. When no current is supplied to theprecipitator the gases will passtherethrough without separation of tarryconstituents and the tarry constituents carried by the gases will becondensed with the oils in the condensers and thus mingled with thefinal product.

The present invention is of more or less Vgeneral application to theoperation of coaldistillation plants, and particularly to byproductcoke-oven plants. It may be utilized, for example, in connection withSemet- Solvay, Koppers and other coke ovens. It will be furtherillustrated by the following more detailed description taken with theaccompanying drawings which show apparatus adapted for the practice ofthe invention. It is intended and will be understood that the inventionis not limited to the specific details of the apparatus as illustratedin the drawino's, in which ig. 1 is a plan view of a portion of acokeloven plant illustrating the application'of the inventiontherethrough;

Fig. 2 is an enlarged sectional view of the electrical precipitator; and

Fig. 3 is a cross sectional view of the precipitator.

Referring to the drawings, 5 indicates a battery of coke ovens in whichthe individual ovens are connected by uptake pipes nd goose-necks 6 to acollector main 7 havin,D a centre box 8. A The collector main isprovided with spray nozzles 9 supplied througha pipe 10 with ammonialiquor or ammonia liquor and tar for' the purpose of cooling the gasesin the collector main. The ammonia liquor and the separated tai` canberwithdrawn ro'il the centre box through a pipe 11. The gases pass fromthe collector main through a crossover main 12 to condensers 13 which ashereinbefore indicated may be ofv the ordinary or Wet. type. Theseparated oil with the ammonia llquor used for cooling escapes through apipe 14 to a decanter 15 where the oil is separated from the ammonialiquor. The oil is delivered through a pipe 16 to a storage tank 17 fromwhich it may be withdrawn asrequired. The ammonia liquor is withdrawnthrough a pipe 18 and delivered to a storage tank 19 from which it maybe returned by a pump 20 to the pipe 10 and to the condensers f 13 forfurther use as a cooling medium. The

gases from the condensers 13 pass through a pipe 21 to an exhauster 22which maintains the pressure balance in the system andare conveyedthence through the equipment (not shown) which separates ammonia, lightoils, etc. from the gases.

To accomplish the purpose of the'presentr invention an electricalprecipitator 23 is disposed in the cross-over main preferably closelyadjacent to the collector main so that all of the gases pass through theelectrical precipitator on their Way to the condensers. The electricalprecipitator comprises a shell enclosing a number of tubes 24 `which aresupported in heads 25 and 26 Within the shell. An inlet 27 near thebottom of thc shell communicates with a chamber 28 which is partiallyseparated from the tube section by a baiie 29. An outlet 30 permits theescape of gases from the separator after the gases have passed throughthe tubes.

A. plurality of electrodes 31, preferably in extends into one of thecasings and is connected to the bus-bar 32, thus supplying the necessarycurrent from any suitable source of unidirectional current under hightension. The flow of current may be controlled by a switch disposed inthe current supply line.,

The casing of the separator is grounded or otherwise connected to thesource of current to complete the circuit. The casing and tubes formthepositive electrode, the electrodes connected to the bus-bar beingnegative. The form and arrangement of the conductors in the circuit canbe varied. The arrangement` should be such as to supply high tensionunidirectional current to the electrodes, thereby permitting acontinuous silent discharge bctween the electrodes and the tubes throughwhich the gases pass.

The gases carrying tar in the form of globules or tar fog, together withsolid particles such as carbon, etc. in finely divided form, thecollector main Iand pass through the tubes in the precipitator, beingsubjected therein to the electrical discharge during the periods whencurrent is supplied. The electrical discharge through ionization of thesolid and liquid particles causes them to separate from the gases andcondensable vapors. The separated liquid, to ether with the solidparticles, run down he inner walls of the tube into the chamber at thebottom of the precipitator and can be withdrawn through a pipe 37. Thegases carrying condensable vapors escape from the top of theprecipitator and are delivered as hereinbefore indicated to thecross-over main 12. By intermittently opening and closing the switchcontrolling the supply of high tension current to the sepentertheelbctrical precipitator from arator a sutlicient proportionof thetarry con- Y stituents is separated from the gases so'that the oil whencondensed contains the propor- .tion of tar required to meet thespecification for coal-tar solution. The exact proportion of the gasesthus subjected to electrical precipitation will be varied, of course, tomeet the conditions imposed by the operationv of the particular cokeoven, that is to say, to permit more or less of the tarry constituentsto pass with the gases to the condensers as may be necessary to producea composite tarry oil suitable for use for creosoting purposes. Theswitch can be adjusted readily to meet these conditions.

The method as described permits the direct production of creosotingcompositions at a coke oven plant in a satisfactory and economicalmanner, utilizing existing equipment. It is particularly advantageous inthat it avoids the expense of tar distillation and the losses of oilthrough cracking incident to such distillation, and gives an improvedcreosoting composition in increased yield directly from the condensingsystem of a coke oven plant.

The new creosoting composition, while comparable with and utilizable asan improved substitute for coal tar solutions, is distinguishedtherefrom in that it is made up of directly recovered constituents,directly recompositions, which comprises passing hot` coal distillationgases into a gas-cleaning device, subjecting the gases to intermittentcleaning therein, and cooling the resulting cleaned and uncleaned gasesto produce a tarry oil of regulated low tar content.

2. The method of producing creosoting compositions. which comprisespassing hot coal distillation gases into a cleaning device, subjectingthe hot gases to intermittent cleaning therein whereby one-half toone-third of the gases are subjected to the cleaning operation,collecting the resulting cleanedA and uncleaned gases, and cooling themto separate a tarry oil of low tar content.

3. The method of producing creosoting compositions, which comprisespassing hot coal distillation gases thru an electrical precipitator,passing a current of high potential thru the precipitator at intervalswhereby the gases passing thru the precipitator are subjected to anintermittent cleaning operation, collecting the resulting cleaned anduncleaned gases and cooling them to separate a tarry oil of low tarcontent.

4. The method of producing creosoting compositions, which comprisespassing hot coal distillation gases thru an electrical precipitator,passing a current of high potential thru the precipitator intermittentlywhereby one-half `to one-third of the gases passing thru theprecipitator are cleaned by electrical precipitation, and collecting theresulting cleaned and uncleaned gases and cooling them to produce atarry oil of low tar content.

5. rIlhe method of preparing creosoting compositions, which comprisespartially cooling hotc'oal distillation gases to separate tarryconstituents therefrom, subjecting the gases intermittently to cleaningby electrical precipitation to separate tarry constituents from aportion of the gases, and cooling the gases to recover a composite oilproduct containing tar.

6. The method of operating the by-product recovery system of a coke ovenbattery, which comprises collecting the coal distillation gases from aplurality of the ovens in a gas collector main, subjecting the gases toregulated cooling therein, passing the resulting gases to a cleaningdevice, and subjecting them to intermittent cleaning therein, wherebyentrained impurities are removed from a portion of the gases, collectingthe resulting cleaned and uncleaned gases, and cooling them to produce atarry oil of low tar content.

7. The improved method of producing tarry oils in the by-productrecovery system ofl coal distillation plants, which comprises tillingunits in which coal is being distilled, passing them thru a cleaning'device at a temperature at which they retain oil constitu- Vcollectingthe 'gases `from all of the coal dis-

